In general, a revolving type construction machine such as a hydraulic excavator, a hydraulic crane or the like is formed of a lower traveling structure as a base, an upper revolving structure as a revolving body that is rotatably mounted on the lower traveling structure, and a working mechanism liftably provided on the front portion side of the upper revolving structure.
The revolving type construction machine has a revolving bearing called so-called revolving ring between the lower traveling structure and the upper revolving structure. The upper revolving structure is revolved and driven in an arbitrary direction on the lower traveling structure by the revolving bearing.
The revolving bearing is composed of a rolling bearing such as a ball bearing, a realer bearing and the like, for example. In the case of an ultra large-sized construction machine, for example, the revolving bearing is composed of a three-row roller bearing formed by combining a two-row thrust roller bearing and a one-row radial roller bearing. Therefore, the revolving bearing can ensure a sufficient load capacity (Patent Document 1).
The thrust roller bearing constituting various types of rotation supporting mechanisms including the revolving bearing is composed of an inner race, an outer race provided on the outer periphery side of the inner race and forming an annular roller accommodating space between itself and the inner race, a plurality of rollers arranged capable of rolling in the roller accommodating space around the roller center axis perpendicular to axes of the inner race and the outer race and extending in the radial direction and a cage provided in the roller accommodating space for retaining each roller capable of rolling. The thrust roller bearing is configured to support the inner race and the outer race capable of relative rotation by rolling of each roller in the roller accommodating space.
On the other hand, a thrust roller bearing configured such that a cage for retaining each roller is configured by a plurality of cage separate bodies arranged separately in the roller accommodating space over the entire periphery of the roller accommodating space is also known (Patent Document 2).